This invention relates to valve assemblies. It has particular application to valves which are used typically in relatively inaccessible locations, e.g. valves of the type which are used in subsea pipelines.
The components of valves, e.g. gate valves which are used in subsea locations are subject to wear, corrosion, and erosion and hence periodically need replacement. It has been proposed to mount the flow control components of such valves, typically the gates and seats, in an insert which can be removably mounted in a receiver receptacle. The receptacle can be coupled to the flow line which the valve controls. This enables the insert to be removed either by a diver or a remotely operated vehicle for the replacement of the valve components. In such arrangements it is necessary to provide a metal seal between the insert and the receiver. In a known arrangement the receiver is provided with tapering faces against which the surface of the insert can seal. The receiver of this arrangement is very complex to produce, the most common method being by casting. However, even when cast the machining is still very complex and it is an expensive process.
The K. B. Bredtschneider et al. U.S. Pat. No. 3,179,121 discloses a ball valve construction with a ball and seats manually removable as a unit. The seats seal against the valve body with elastomeric seal means on a tapered surface.
The M. R. Jones U.S. Pat. No. 3,589,674 discloses another ball valve structure with a second pressure balancing stem in which the the ball, seats and balance stems are manually removable as a unit.
The J. A. Burkhardt et al. U.S. Pat. No. 3,799,191 discloses a gate valve structure with a removable body containing the gate, seats, stem and stem operating means. The removable body is secured to the valve body by a lock ring.
The R. L. Ripert U.S. Pat. No. 4,387,735 discloses a valve structure removable from a pipeline wherein the valve is received within a support structure attached to the pipeline. The support structure has seal rings mounted therein which a worm gear mechanism activates into engagement with the removable valve structure to form a fluid tight conduit.
The R. L. Ripert U.S. Pat. No. 4,431,022 discloses a removable valve structure received within a support structure similar to that of the '735 patent. The valve structure has all components mounted therein, including a sealing means on each end of the valve which is biased outwardly to engage parallel plates on the support structure. A pressure responsive means for moving the seal rings inwardly during installation and removal is also disclosed.
The J. E. Lawson U.S. Pat. No. 4,874,008 discloses a valve mounting structure whereby hydraulic studs are used to secure a valve body between mounting members which are part of a block manifold used in oil and gas production.